Model Code

Integrated Biosphere Simulator (IBIS)

The Earth’s terrestrial (land-based) ecosystems are critically important to the welfare of humankind. Food, fiber, fresh water, medicines, and forest products are all derived from our terrestrial ecosystems. In addition, terrestrial ecosystems play a central role in regulating the biogeochemical and climate systems of this planet.

To better understand ecological processes, and to evaluate their response to human activity, our research team developed IBIS (the Integrated Biosphere Simulator), a comprehensive computer model of the Earth’s terrestrial ecosystems.

IBIS simulates a wide variety of ecosystem processes, including:

  • Energy, water, and carbon dioxide exchange between plants, the atmosphere, and the soil
  • Physiological processes of plants and soil organisms, including photosynthesis and respiration
  • Seasonal changes of vegetation, including spring budburst, fall senescence, and winter dormancy
  • Plant growth and plant competition
  • Nutrient cycling and soil processes

IBIS is one of the few computer models to incorporate this range of processes in a single framework.

We have used the model to study how ecosystems respond to changes in land use and climate. The IBIS model was tested against detailed field measurements collected from ecosystems around the world.

IBIS is described in these two articles:

  • Kucharik, C.J., J.A. Foley, C. Delire, V.A. Fisher, M.T. Coe, J. Lenters, C. Young-Molling, N. Ramankutty, J.M. Norman, and S.T. Gower (2000). Testing the performance of a dynamic global ecosystem model: Water balance, carbon balance and vegetation structure. Global Biogeochemical Cycles 14(3), 795-825.
  • Foley, J.A., I.C. Prentice, N. Ramankutty, S. Levis, D. Pollard, S. Sitch, and A. Haxeltine (1996). An integrated biosphere model of land surface processes, terrestrial carbon balance, and vegetation dynamics. Global Biogeochemical Cycles 10(4), 603-628.


Please note: This code is available only to check the model as it was used in our research papers. Due to funding constraints, we cannot offer technical help on an individual basis.

Terrestrial Hydrology Model with Biogeochemistry (THMB) — Formerly HYDRA

The Earth’s freshwater systems, as sources of potable water, hydroelectric power and food, are of great importance to human society.

Our research is focused on the linkages between climate, land cover, and the behavior of whole watersheds — including lakes, wetlands, rivers and groundwater systems. In particular, we are interested in how land use and variations in climate can affect the availability and quality of fresh water resources. In order to help answer these questions, we developed computer modeling tools to examine the impact of human activities on freshwater supplies across the globe.

The THMB (Terrestrial Hydrology Model with Biogeochemistry) model (formerly known as HYDRA), simulates the flow of water through groundwater systems, rivers, lakes and wetlands. THMB is one of the few hydrological models that simulate the complete freshwater system.

THMB (HYDRA) is described in:

  • Coe, M.T. 2000: Modeling terrestrial hydrological systems at the continental scale: Testing the accuracy of an atmospheric GCM, Journal of Climate, 13, 686-704

You may view the README file describing THMB (HYDRA), the NetCDF README file, or the HDF README file prior to downloading anything.

Please contact Mike Coe at with any questions.